Microwave assisted beta glucan extraction from hulless barley

This thesis was carried out with the aim of extracting beta glucan in high yield and purity from barley, which is one of the most grown grains in our country. Hulless barley, which has a higher beta glucan content, was chosen for extraction. Microwave assisted high pressure CO2/H2O was used as the extraction method. This method has been tried for the first time in the world. The optimum conditions for extraction were determined as temperature 47.74 °C, time 19.92 minutes and water: barley flour ratio 10.10:1. Under these conditions, beta glucan yield was determined as 62.43±1.39% and beta glucan purity was determined as 67.17±0.57%. In addition, beta glucan extract was obtained in higher yield and purity compared to classical aqueous extraction (p<0.05). The developed method has the advantage of using less solvent (15:1; 10.10:1) in a shorter time (180 minutes; 19.92 minutes). It is important to extract beta glucan, which has many health benefits such as reducing total cholesterol and low-density lipoprotein (LDL) cholesterol, inhibiting postprandial glucose increase, reducing mucosal damage in chronic gastritis, improving the immune system, and being an immunomodulator, without damaging its molecular structure. For this reason, it has been compared with the classical aqueous extraction, which is the most used in the literature. Characterization of beta glucan extracts obtained by both methods has been described. Composition analysis of the extracts, more beta glucan, protein, starch, ash, arabinoxylan, lignin and other substances were extracted with the developed method (p <0.05). In terms of molecular weights, high molecular weight extraction was achieved. Weight average molecular weight (Mw) was not statistically significant, but the statistically developed method was found to be more advantageous in terms of number average molecular weight (Mn), peak molecular weight (Mp) and polydispersity index (PDI) (p<0.05). The extracts obtained by microwave-assisted high pressure CO2/H2O extraction method have a higher molecular weight, therefore their water solubility is lower (69.4±2.25%) and their water holding capacity (8.05±0.18%) is higher (p<0.05). Fourier Transform Infrared Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC) properties of the extracts are similar. It has been determined that the extracts are heat resistant and suitable for cooking and industrial use as a thickener due to their water retention capacity. When the color of the extracts is compared, the developed method is statistically brighter and less yellow than the classical method. Additionally, both extracts have similar morphological images. The resulting beta glucan extract has the potential to be used as a nutritional supplement or food additive due to its health benefits.